Self-contained total internal reflection sub-assembly

ABSTRACT

A total internal reflection sub-assembly includes a body defining at least a portion of an optical path, a lens supported by the body and positioned in the optical path, and an optical turning member supported by the body and configured to change the direction of the optical path. The total internal reflection sub-assembly also includes a carrier having a first surface coupled to the body and a second surface opposite the first surface. An active device is supported on the first surface of the carrier, which is coupled to the body on opposite sides of the active device. The body and carrier are shaped so that a space is maintained between the active device and an underside surface of the body. The lens is positioned on the underside surface and aligned with the active device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §119 ofU.S. Provisional Application Ser. No. 61/806,166 filed on Mar. 28, 2013,the content of which is relied upon and incorporated herein by referencein its entirety.

BACKGROUND

The disclosure relates generally to electric-optical systems, and moreparticularly to total internal reflection sub-assemblies used in fiberoptic sub-assemblies for active optical cable assemblies or the like.

Short-distance data links used for consumer electronics are reachingincreasingly higher data rates, especially those used for video and datastorage applications. Examples include the USB 3.0 protocol at 5 Gb/s,HDMI at 10 Gb/s and Thunderbolt™ at 10 Gb/s over two channels. At suchhigh data rates, traditional copper cables have limited transmissiondistance and cable flexibility. For at least these reasons, opticalfiber is emerging as an alternative to copper wire for accommodating thehigh data rates for the next generations of electronic devices such asconsumer devices.

Unlike telecommunication applications that employ expensive, high-poweredge-emitting lasers along with modulators, short-distance optical fiberlinks are based on low-cost, low-power, directly-modulated light sourcessuch as vertical-cavity surface-emitting lasers (VCSELs). In general,optical fiber links include fiber optic assembles that are used tocouple light from the light source into an optical fiber in onedirection (i.e., transmit). The fiber optic assemblies are also used tocouple light traveling in another optical fiber onto a photodiode in theother direction (i.e., receive). To be viable for consumer electronicsand the like, the fiber optic assemblies need to be low-cost. Thisrequirement drives the need for designs that are simple to manufactureyet have suitable performance.

SUMMARY

Embodiments of a total internal relection (TIR) sub-assembly aredisclosed herein. The TIR sub-assembly may be part of a fiber opticsub-assembly, which in turn may be part of an active optical cableassembly (and specifically connectors of such active optical cableassemblies, examples of which are also disclosed).

According to one embodiment, a TIR sub-assembly includes a body definingat least a portion of an optical path, a lens supported by the body andpositioned in the optical path, and an optical turning member supportedby the body and configured to change the direction of the optical path.The TIR sub-assembly also includes a carrier having a first surfacecoupled to the body and a second surface opposite the first surface. Anactive device is supported on the first surface of the carrier, which iscoupled to the body on opposite sides of the active device. The body andcarrier are shaped so that a space is maintained between the activedevice and an underside surface of the body. The lens is positioned onthe underside surface and aligned with the active device.

One of the benefits of such a TIR sub-assembly is that it is aself-contained sub-assembly including the active device and lens. Thisnot only allows the active device and lens to be pre-aligned (i.e.,aligned before supporting the TIR sub-assembly on a printed circuitboard), but also allows the optical system to be tested independently ofany printed circuit board on which the TIR sub-assembly is to be placed.

Corresponding methods of manufacturing are also disclosed. To this end,one method for manufacturing a TIR sub-assembly involves providing abody that defines at least a portion of an optical path. The bodysupports a lens that is positioned in the optical path and an opticalturning member that is configured to change the direction of the opticalpath. The method also involves supporting an active device on a firstsurface of a carrier, and coupling the first surface of the carrier tothe body on opposite sides of the active device. Consistent with theembodiment mentioned above, the body and carrier are shaped so that aspace is maintained between the active device and an underside surfaceof the body. Additionally, the lens is positioned on the undersidesurface of the body and aligned with the active device.

Some methods may involve additional steps to manufacture a fiber opticsub-assembly. One such method involves providing a printed circuit boardhaving first and second surfaces and separately providing a TIRsub-assembly consistent with the embodiment mentioned above. The TIRsub-assembly is then supported on the printed circuit board, which isshaped to receive the carrier of the TIR sub-assembly proximate thesecond surface so that at least a portion of the optical path betweenthe active device and lens of the TIR sub-assembly is located betweenthe first and second surfaces of the printed circuit board. Testing maybe performed on the TIR sub-assembly prior to this step to verifyperformance of the active device and optical path.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,together with the description, serve to explain the objects, advantages,and principles of the invention. In the drawings:

FIG. 1 is a perspective view, partially cut-away, of a connector for anactive optical cable, wherein the connector includes a fiber opticsub-assembly having a known configuration;

FIG. 1A is an enlarged view of the area circled in FIG. 1;

FIG. 2 is a perspective view, partially cut-away, of a connectorincluding a fiber optic sub-assembly according to one embodiment;

FIG. 3 is a perspective view, partially cut-away and similar to FIG. 2,but showing an opposite side of the connector and fiber opticsub-assembly;

FIG. 4 is a perspective view showing the fiber optic sub-assembly ofFIGS. 2 and 3 in isolation;

FIG. 5 is a perspective view of a portion of the fiber opticsub-assembly of FIGS. 2 and 3;

FIG. 6 is an exploded perspective view of a total internal reflectionsub-assembly included in the fiber optic sub-assembly shown in FIG. 5;

FIG. 7 is a perspective view of the fiber optic sub-assembly of FIGS. 2and 3, wherein the fiber optic sub-assembly is illustrated in isolationand from a different angle;

FIG. 8 is an exploded perspective view of the fiber optic sub-assemblyshown in FIG. 7;

FIG. 9 is a cross-sectional perspective view taken along line 9-9 inFIG. 7;

FIG. 10 is a cross-sectional elevation view taken along line 10-10 inFIG. 7;

FIG. 11 is a side elevation view of a fiber optic sub-assembly having aknown configuration;

FIG. 12 is a perspective view of a total internal reflectionsub-assembly according to another embodiment;

FIG. 13 is a perspective view of an embodiment of a fiber opticsub-assembly including the total internal reflection assembly of FIG.12; and

FIG. 14 is a cross-sectional side view of a portion of the fiber opticsub-assembly shown in FIG. 13.

DETAILED DESCRIPTION

Reference will now be made in detail to fiber optic sub-assemblies foractive optical cable assemblies, with examples of the latter beingillustrated in the accompanying drawings. Wherever possible, the samereference numbers will be used throughout the drawings and descriptionto refer to the same or like parts.

Some of the drawings show the fiber optic sub-assemblies within aconnector of an active optical cable assembly. The active optical cableassemblies may be used in the consumer electronics field. For example,the connectors may be USB, Thunderbolt, HDMI, or PCI Express connectors.However, the disclosure is not limited to such connectors or consumerelectronics applications. Other optical cable assemblies andapplications are possible for the fiber optic sub-assemblies describedherein.

With this mind, FIGS. 1 and 1A illustrate a known arrangement for afiber optic sub-assembly 20 within a connector 22 of an active opticalcable assembly 10. The fiber optic sub-assembly 20 includes a printedcircuit board 24 and total internal reflection (TIR) sub-assembly 26supported on the printed circuit board 24. The TIR sub-assembly 26includes one or more active devices 28 (four are shown in theillustrated embodiment) electrically coupled to the printed circuitboard 24 and optically coupled to a respective optical fiber 30. To thisend, the TIR sub-assembly 20 defines optical paths between the activedevices 28 and optical fibers 30, which extend into the connector 20from a cable 12 that bundles and protects the optical fibers 30.

The active devices 28 may be light sources, such as vertical-cavitysurface-emitting lasers (VCELs), or light detectors, such asphotodiodes. Light traveling from the active devices 28 to the opticalfibers 30 is collected by lenses (not shown in FIGS. 1 and 1A) in eachof the optical paths and directed to an optical turning member 32(typically an angled mirror), which then reflects the lightapproximately 90 degrees toward ends of the optical fibers 30.Conversely, light traveling from the optical fibers 30 to the activedevices 28 is reflected by the optical turning member 32 towards thelenses, which concentrate and direct the light at the active devices 28.Thus, there is a change in direction in the optical paths between theoptical fibers 30 and active devices 28. The distance of the opticalfibers 30 from the optical turning member 32, which may either be acommon or respective optical turning member 32, depends on the design ofthe optical system (e.g., the type of active device 28, size of lens inthe optical path, etc.).

The lenses in a TIR sub-assembly like the one shown in FIG. 1 are spaceda specific distance from the active devices 28, with an air gapmaintained therebetween, based on the properties of the active devices28 (e.g., the optical power) and other considerations familiar topersons skilled in the design of optical systems. The need for thisspacing and the presence of the optical turning member 32 (e.g., one ormore angled mirrors) for changing the direction of the optical pathsinfluences the overall height of the TIR sub-assembly 26. This heightmay even be greater than other components on the printed circuit board24 and thereby influence the overall profile, or “stack height,” of thefiber optic sub-assembly 20. Furthermore, the need to support the lensesover the active devices 28 may restrict or limit the placement ofpassive devices 34 close to the active devices 28. Such passive devices34 may include transimpedance amplifiers, resistors, capacitors,inductors, and other circuit components electrically coupled to one ormore chips 36 on the printed circuit board 42. Increasing the distancebetween the active devices 28 and passive devices 34 may increase lossesbeyond acceptable limits at high transmission rates.

For example, passive components such as a capacitor are sometimes neededto reduce noise in the signal from an active component like aphotodiode. The capacitor provides a low impedance at high frequenciesso that power supply noise does not couple through the photodiode'sinternal capacitance and reach other passive components connected to thephotodiode, such as a transimpedance amplifier. But the wires or tracesthat connect the capacitor to the photodiode tend to negate the lowimpedance by acting as a series inductor, which has an impedance thatrises linearly with frequency. The longer the wires or traces, the morethey negate the desired low impendance (and resulting short circuit)provided by the capacitor at high frequencies. Additionally, sufficientinductance may introduce an unwanted resonant frequency in the circuit.

FIGS. 2 and 3 illustrate an exemplary embodiment of new arrangement fora fiber optic sub-assembly 40 intended to address some of theabove-mentioned challenges. Like FIG. 1, FIGS. 2 and 3 illustrate thefiber optic sub-assembly 40 within the connector 22 of an active opticalcable assembly 10. Different views are provided to show opposite sidesof a printed circuit board 42 in the fiber optic sub-assembly 40. FIG. 4illustrates the fiber optic sub-assembly 40 in isolation for both views.In general, the printed circuit board 42 has opposed first and secondsurfaces 44, 46. A total internal reflection (TIR) sub-assembly 48 is atleast partially integrated into the printed circuit board 42 andsupported thereby. The configuration is such that the overall stackheight (i.e., profile) defined by the printed circuit board 42 andintegrated TIR sub-assembly 48 is less than a non-integratedconfiguration involving the same components. In other words, thedistance between the first and second surfaces 44, 46 defines a printedcircuit board height. The distance between lowermost and uppermostportions of the TIR sub-assembly 48 defines a nominal height of the TIRsub-assembly 48. The overall stack height referred to above is less thanthe sum of the printed circuit board height the nominal height of theTIR sub-assembly.

Reference will now be made to FIGS. 5-10 to describe the fiber opticsub-assembly 40 in further detail. As mentioned above, the embodiment ismerely an example; different embodiments of the new arrangementmentioned above will be appreciated by persons skilled in the art. Asshown in FIGS. 5 and 6, the TIR sub-assembly 48 in this embodimentincludes four active devices 28 and four lenses 52. Each active device28 and lens 52 is associated with a corresponding optical path definedby the TIR sub-assembly 48. Four active devices 28 and four lenses 52are provided in the embodiment shown (e.g., for four different opticalpaths), although more or fewer may be provided in alternativeembodiments.

At least a portion of the optical path between each active device 28 andlens 52 is located between the first and second surfaces 44, 46 of theprinted circuit board 42. For example, the printed circuit board 42 mayinclude an opening or hole 54 to allow components of the TIRsub-assembly 48 to be supported on opposite sides of the printed circuitboard 42. In the embodiment shown, the TIR sub-assembly 48 includes abody 56 coupled to the side of the printed circuit board 42 thatincludes the first surface 44. The body 56 supports the optical fibers30, optical turning member 32, and lenses 52. The optical fibers 30 maybe supported in V-grooves (not numbered in FIGS. 5-10) on an uppersurface of the body 56, for example, and may extend in a planesubstantially parallel to the first surface 44 of the printed circuitboard 42. The lenses 52 are supported on an underside surface 58 (FIG.10) that faces the first surface 44 of the printed circuit board 42. Thebody 56 is positioned on the printed circuit board 42 so that lenses 52are aligned with the opening 54 in the printed circuit board 42. FIGS.7-10 illustrate these aspects in further detail.

As shown in FIGS. 7-10, the body 56 may be designed to rest on the firstsurface 44 of the printed circuit board 42. The body 56 may also beshaped so that the underside surface 58 with the lenses 52 at leastpartially covers or overhangs the opening or hole 54. Fiducial features60 (e.g., holes or other reference structures) are provided on theprinted circuit board 42 to properly align and position the body 56 (andlenses 52 supported thereby) relative to the printed circuit board 42.As will be described in greater detail below, the body 56 may includealignment features 64 (e.g., fiducial holes, projections, or otherstructures) configured to cooperate with the fiducial features 60 forthis purpose.

FIG. 10 illustrates how at least a portion of each lens 52 extends intothe opening 54 in the printed circuit board 42 so as to be offset fromthe first surface 44 in a direction towards the second surface 46. Thisis due to the body 56 resting on the first surface 44. In alternativeembodiments, the printed circuit board 42 may include a recess or slotthat receives the body 56 so that a lower surface of the body 56 is alsooffset from the first surface 44 of the printed circuit board 42 in adirection towards the second surface 46. The lenses 54 in suchembodiments may therefore be positioned closer to the active devices 28,if necessary based on the design of the optical system. Arrangementswill also be appreciated where the body 56 is shaped to support thelenses 54 above the first surface 44.

Referring back to FIGS. 5-10 in general, the TIR sub-assembly 48 in theembodiment shown further includes a carrier 66 coupled to the secondsurface 46 of the printed circuit board 42. The carrier 66 at leastpartially covers the opening 54 in the printed circuit board 42 andsupports the active devices 28 on an upper surface 68 (FIGS. 9 and 10)that faces the lenses 52. The active devices 28 may be, for example,wire-bonded to pads on the carrier 66. Conductors or other electricallinks or traces (not shown) on the carrier 66 and printed circuit board42 may be used to electrically couple the active devices 28 to one ormore passive devices 34. The active devices 28 may alternatively oradditionally be bonded to the carrier 66 using conductive epoxy.

Alignment of the active devices 28 and lenses 52 may be achieved byusing the contours of the carrier 66 as a reference for positionregistration of the active devices 28. The carrier 66 may then becoupled to the printed circuit board 42 with a vision system that usesthe fiducial features 60 as a reference. Because the alignment features64 on the body 56 cooperate with the fiducial features 60 to positionthe body 56 on the printed circuit, the lenses 52 on the body 56 are, ineffect, located using the fiducial features 60 as references as well.Other alignment schemes are possible, however, including those using a“look up/look down” optical alignment system.

For example, the carrier 66 with the active devices 28 may first becoupled to the printed circuit board 42. A beam splitter (not shown) maythen be positioned somewhere between the active devices 28 and the body56, with the latter being moved in a horizontal plane (i.e., X andY-directions in a reference coordinate system) until the active devices28 are aligned with the lenses 52. At this point the beam splitter maybe removed and the body 56 and/or printed circuit board 42 may be movedvertically (i.e., in a Z-direction) until the two contact each other.The geometries are such that upon contact, the proper distance ispresent between the active devices 28 and lenses 52 for the particularoptical system design. The body 56 may be bonded in place to the printedcircuit board 42 after this positioning using a quick-curing adhesive,such as a UV-curing adhesive, or fixed in position using other knowntechniques.

In alternative embodiments not shown herein, the opening 54 in theprinted circuit board 42 may be a recess or well with a bottom surface.The active devices 28 may be positioned on the bottom surface of therecess or well such that a carrier is not needed. Persons skilled in theart will appreciate other variations of the types of arrangementsdescribed above, where the active devices 28 are offset from the firstsurface 44 of the printed circuit board 42 in a direction towards thesecond surface 46 and the printed circuit board 42 is shaped so that aspace is maintained between the active devices 28 and lenses 52.

As can be appreciated, the TIR sub-assembly 48 makes use of space in theprinted circuit board 42 to provide the fiber optic sub-assembly 40 witha lower profile than known arrangements. This can best be appreciated bycomparing FIG. 10, which illustrates a portion of the fiber opticsub-assembly 40, to FIG. 11, which illustrates a portion of the fiberoptic sub-assembly 20. Positioning the active devices 28 proximate orotherwise closer to the second surface 46 of the printed circuit board42 enables the lenses 54 to be supported proximate or below the firstsurface 44 (like in FIG. 10) rather than above the first surface 46(like in FIG. 11). The overall stack height is reduced considerablywhile maintaining the required space between the active devices 28 andlenses 52, thereby helping the fiber optic sub-assembly 40 meet thedifficult space requirements for standard connector packages in theconsumer electronics field or the like.

Moreover, positioning the component of the TIR sub-assembly 48 thatsupports the optical fibers 30 and lenses 52 (i.e, the body 56) on anopposite side of the printed circuit board 42 than the active devices 28allows the passive devices 34 (FIGS. 7 and 8) to be positioned muchcloser to the active devices 28. Short electrical path lengths arepossible, which results in improved signal to noise performance. Theincreased freedom to position the passive devices 34 is particularlyadvantageous for TIR sub-assemblies including more two or more opticalfibers (and, therefore, two or more optical paths/channels) because thenumber of passive devices required increases with the number of opticalfibers. Positioning the increased number of passives devices closeenough to the active devices so that signal to noise losses remainwithin acceptable levels can be a challenge, especially when there arefour or more optical paths/channels. By not having the body 56 limit thepositioning of the passive devices 34 and by providing a lowprofile/stack height, this challenge can be met in a manner so that alarge number of optical paths/channels (e.g., four or more) may beprovided with the fiber optic sub-assembly still fitting within standardconnector packages.

FIG. 12 illustrates a TIR sub-assembly 80 according to an alternativeembodiment, and FIGS. 13 and 14 illustrate the TIR sub-assembly 80 aspart of a fiber optic sub-assembly 82. The TIR sub-assembly 80 may be atleast partially integrated with a printed circuit board 42 of the fiberoptic sub-assembly 82 such that the advantages mentioned above applyequally to this embodiment. The manner in which the integration isachieved is different, however, due to the TIR sub-assembly 80 having adifferent configuration.

In particular, the carrier 66 supporting the active devices 28 iscoupled to the body 56 of the TIR sub-assembly 80 rather than to theprinted circuit board 42. The body 56 is shaped to support the carrier66 on opposite sides of the active devices 28 and to maintain a spacebetween the active devices 28 and lenses 52. In the embodiment shown,the body 56 includes first and second portions 84, 86 extending from theunderside surface 58 on opposite sides of the lenses 52. The firstportion 84 is prismatic or block-like and provides support for theportion of the body 56 on which the optical fibers 30 are disposed. Thesecond portion 86 is also prismatic or block-like, but has a smallerwidth or thickness than the first portion 84. To this end, the firstportion 84 may be considered a main support for the body 56 while thesecond portion 86 may be considered a support rim that is spaced fromthe main support. The space maintained between the upper surface 68 ofthe carrier 66 on which the active devices 28 are disposed and theunderside surface 58 of the body 56 on which the lenses 52 are disposedforms a passage between the first and second portions 84, 86. Inalternative embodiments, the first and second portions 84, 86 may bejoined so that the space takes the form of hole or well in the body 56(e.g., with the underside surface 58 being a bottom surface of the holeor well). Other shapes and configurations of the body 56 that allow theupper surface 68 of the carrier 66 to be coupled to the body 56 onopposite sides of the active devices 28 will be appreciated by personsskilled in the art.

The printed circuit board 42 is shaped to receive the TIR sub-assembly80, as shown in FIGS. 13 and 14. To this end, a slot or recess (notnumbered) may be formed in the first surface 44 of the printed circuitboard 42 to accommodate the first and second portions 84, 86 of the body56. Additionally, an opening 90 extends through the printed circuitboard 42 to the second surface 46 thereof to accommodate the carrier 66.

The alignment features 64 on the body 56 cooperate with correspondingfiducial features 60 on the printed circuit board 42 to help enableproper positioning of the TIR sub-assembly 80 (and particularly theactive devices 28) relative to the printed circuit board 42. Thealignment features 64 may be in the form of fiducial holes or alignmentpins, for example. Persons skilled in the art of electric-opticalsystems will appreciate more detailed aspects of positioning processesthat use such alignment features and fiducial features. In terms of theTIR sub-assembly 80, however, note that the active devices 28 may bepositioned relative to the lenses 52 prior to supporting the TIRsub-assembly 80 on the printed circuit board 42. This pre-alignment maybe achieved, for example, by using the alignment features 64 (e.g.,fiducial holes) as a positional reference when coupling the carrier 66to the body 56. The alignment features 64 have an accurate location withrespect to lenses 52 and are used to position the body 56 relative tothe printed circuit board 42 (as discussed above). Positioning theactive devices 28 relative to the lenses 52 in this manner may result ina smaller tolerance stack-up and thereby provide better alignmentbetween the active devices 28 and lenses 52. Moreover, aligning theactive devices 28 and lenses 52 only with reference to the TIRsub-assembly 80 directly may reduce or relax the accuracy required forpositioning the body 56 relative to the printed circuit board 42.

As can be appreciated from FIG. 13, the fiber optic sub-assembly 82still allows passive devices 34 to be positioned in close proximity tothe active devices 28. Conductors 92 may be electrically coupled to theactive devices 28 and extend through the carrier 66 to lower surface 94of the carrier 66. Additional conductors or electrical leads/traces (notshown) then electrically couple the conductors to the passive devices 34on the printed circuit board 42. If desired, some passive devices 34 mayeven be supported on a lower surface 94 of the carrier 66.

One of the benefits of the fiber optic sub-assembly 82 is that it is aself-contained sub-assembly including the active devices 28 and lenses52. This not only allows the active devices 28 and lenses 52 to bepre-aligned (i.e., aligned before supporting the TIR sub-assembly 80 onthe printed circuit board 42) as discussed above, but also allows theoptical system to be tested independently of the printed circuit board42. If for some reason the optical system does not function properly,only the TIR sub-assembly 80 is lost. The printed circuit board 42 andits electronic components are not affected by the failure/loss becausethey were never connected the TIR sub-assembly 80. In other words,losses the entire fiber optic sub-assembly 82 need not be replaced.

It will be apparent to those skilled in the art that variousmodifications and variations can be made without departing from thespirit or scope of the invention. For example, the TIR sub-assembly 80is illustrated with the carrier 66 having a smaller footprint area thanthe body 56. No portion of the carrier 66 extends transversely beyondthe body 56. In alternative embodiments, portions of the carrier 66 mayextend in this manner such that the portions do not face/confront thebody 56.

Since these and other modifications combinations, sub-combinations andvariations of the disclosed embodiments incorporating the spirit andsubstance of the invention may occur to persons skilled in the art, theinvention should be construed to include everything within the scope ofthe appended claims and their equivalents.

What is claimed is:
 1. A total internal reflection sub-assembly,comprising: a body defining at least a portion of an optical path anddefining a footprint area; a lens supported by the body and positionedin the optical path; an optical turning member supported by the body andconfigured to change the direction of the optical path; a carrier havinga first surface coupled to the body and a second surface opposite thefirst surface, and the carrier has a footprint area smaller than thefootprint area of the body; and an active device supported on the firstsurface of the carrier, wherein the first surface of the carrier iscoupled to the body on opposite sides of the active device, the body andcarrier being shaped so that a space is maintained between the activedevice and an underside surface of the body, and the lens beingpositioned on the underside surface of the body and aligned with theactive device.
 2. The total internal reflection sub-assembly of claim 1,wherein the space maintained between the active device and an undersidesurface of the body is defined by first and second portions of the bodyextending from the underside surface on opposite sides of the lenses. 3.The total internal reflection sub-assembly of claim 1, furthercomprising: an optical fiber supported by the body, the optical pathextending between the optical fiber and the active device.
 4. The totalinternal reflection sub-assembly of claim 1, further comprising: aconductor electrically coupled to the active device , the conductorextending through the carrier to the second surface thereof.
 5. Thetotal internal reflection sub-assembly of claim 4, further comprising: apassive device supported on the second surface of the carrier, thepassive device being electrically coupled to the active device by theconductor.
 6. The total internal reflection sub-assembly of claim 1,wherein the body includes at least one alignment feature configured tocooperate with a fiducial feature on a printed circuit board.
 7. Thetotal internal reflection sub-assembly of claim 1, wherein the activedevice is wire-bonded to pads on the first surface of the carrier. 8.The total internal reflection sub-assembly of claim 1, wherein the bodydefines at least a portion of two or more optical paths and the totalinternal reflection sub-assembly comprises two or more lenses and two ormore active devices associated with the two or more optical paths. 9.The total internal reflection sub-assembly of claim 8, wherein bodydefines at least four optical paths and the total internal reflectionsub-assembly comprises at least four lenses and at least four activedevices associated with the at least four optical paths.
 10. The totalinternal reflection sub-assembly of claim 8, wherein at least one of theactive devices comprises a light source and at least another of theactive devices comprises a light detector.
 11. The total internalreflection sub-assembly of claim 10, wherein the light source comprisesa vertical cavity surface-emitting laser and the light detectorcomprises a photo diode.
 12. A fiber optic sub-assembly, comprising: aprinted circuit board having opposed first and second surfaces, whereinone of the first and second surfaces is an upper surface of the printedcircuit board and the other of the first and second surfaces is a lowersurface of the printed circuit board; and a total internal reflectionsub-assembly supported by the printed circuit board, the total internalreflection sub-assembly comprising: a body defining at least a portionof an optical path; a lens supported by the body and positioned in theoptical path; an optical turning member supported by the body andconfigured to change the direction of the optical path; a carrier havinga first surface coupled to the body and a second surface opposite thefirst surface; and an active device supported on the first surface ofthe carrier, wherein the first surface of the carrier is coupled to thebody on opposite sides of the active device, the body and carrier beingshaped so that a space is maintained between the active device and anunderside surface of the body, and the lens being positioned on theunderside surface of the body and aligned with the active device;wherein the printed circuit board is shaped to receive the carrier ofthe total internal reflection sub-assembly proximate the second surfaceso that at least a portion of the optical path between the active deviceand lens of the total internal reflection sub-assembly is locatedbetween the first and second surfaces of the printed circuit board. 13.The fiber optic sub-assembly of claim 12, wherein the printed circuitboard includes an opening on the second surface shaped to receive thecarrier of the total internal reflection sub-assembly and a recess inthe first surface shaped to receive the body of the total internalreflection sub-assembly.
 14. The fiber optic sub-assembly according toclaim 12, wherein the printed circuit board includes one or morefiducial features and the body of the total internal reflectionsub-assembly includes one or more alignment features cooperating withthe fiducial features to position the total internal reflectionsub-assembly relative to the printed circuit board.
 15. An activeoptical cable assembly, comprising: a cable with at least one opticalfiber; a connector coupled to an end of the cable; and a fiber opticsub-assembly disposed within the connector, the fiber optic sub-assemblycomprising: a printed circuit board having opposed first and secondsurfaces, wherein one of the first and second surfaces is an uppersurface of the printed circuit board and the other of the first andsecond surfaces is a lower surface of the printed circuit board; and atotal internal reflection sub-assembly supported by the printed circuitboard, the total internal reflection sub-assembly comprising: a bodydefining at least a portion of an optical path; a lens supported by thebody and positioned in the optical path; an optical turning membersupported by the body and configured to change the direction of theoptical path; a carrier having a first surface coupled to the body and asecond surface opposite the first surface; and an active devicesupported on the first surface of the carrier, wherein the first surfaceof the carrier is coupled to the body on opposite sides of the activedevice, the body and carrier being shaped so that a space is maintainedbetween the active device and an underside surface of the body, and thelens being positioned on the underside surface of the body and alignedwith the active device; wherein the printed circuit board is shaped toreceive the carrier of the total internal reflection sub-assemblyproximate the second surface so that at least a portion of the opticalpath between the active device and lens of the total internal reflectionsub-assembly is located between the first and second surfaces of theprinted circuit board.
 16. The active optical cable assembly of claim15, wherein the connector comprises a USB, Thunderbolt, HDMI, or PCIExpress connector.
 17. A method of manufacturing a total internalreflection sub-assembly, comprising: providing a body that defines atleast a portion of an optical path and defining a footprint area,wherein the body supports a lens that is positioned in the optical pathand an optical turning member that is configured to change the directionof the optical path; supporting an active device on a first surface of acarrier, wherein the carrier includes a second surface opposite thefirst surface, and the carrier has a footprint area smaller than thefootprint area of the body; coupling the first surface of the carrier tothe body on opposite sides of the active device, wherein the body andcarrier are shaped so that a space is maintained between the activedevice and an underside surface of the body, and further wherein thelens is positioned on the underside surface of the body and aligned withthe active device.
 18. The method of claim 17, further comprising:providing a printed circuit board with opposed first and secondsurfaces, wherein one of the first and second surfaces is an uppersurface of the printed circuit board and the other of the first andsecond surfaces is a lower surface of the printed circuit board, theprinted circuit board having at least one passive device positioned onthe second surface; and supporting the total internal reflectionsub-assembly on the printed circuit board, wherein the printed circuitboard is shaped to receive the carrier of the total internal reflectionsub-assembly proximate the second surface so that at least a portion ofthe optical path between the active device and lens of the totalinternal reflection sub-assembly is located between the first and secondsurfaces of the printed circuit board.
 19. The method of claim 18,wherein a testing step is carried out prior to supporting the totalinternal reflection sub-assembly on the printed circuit board.
 20. Themethod of claim 17, further comprising: testing the total internalreflection sub-assembly to verify performance of the active device andoptical path.